refactor: Unify eslint config, convert to flat configs and update plugins (WIP)

[cacieprins]

• Closes Remove dependency on ESLint v8 (EOL) #30386

Additional details

This is a first step to working towards our Typescript north star.

The big, structural changes:

• npm/eslint-plugin-dev is removed. The custom rules defined there are available from eslint-plugin-cypress and eslint-plugin-mocha, or were ignored in places they would have applied.
• Eslint is updated to 9.18
• Eslint config is converted to the newer flat format
• eslint-stylistic is used for formatting rules that were deprecated. We should consider moving the prettier, but this is a good first step.
• Recommended rulesets are imported from the plugins we leverage
  • "Gold standard" rules that fail against the repo are turned off, and should be turned to 'warn' before merging. They're in a special section in the baseConfig.
  • Stylistic rules that were previously applied inconsistently across the repo are turned off, to limit the diff size of this PR. They should be enabled in a follow-up PR.

Benefits:

• Working towards enabling gold standard rules will be easier
• Using a base 'recommended' ruleset from the plugins we use aligns standards with other projects
• Fewer complicated special-cases for rules
• Dogfooding our own eslint-plugin-cypress

Some drawbacks:

• GraphQL linting is not as comprehensive. This is mostly due to the major version of graphql that the repo and some of its other related dependencies require. Upgrading graphql is out of scope for the forseeable future - it will require an enormous reworking of packages/data-context and packages/graphql. Because this area of the code isn't currently modified very often, I think this is an okay tradeoff.
• Vue linting is slow. That's because it's being processed both by ts and by vue. It takes approximately 1 second per .vue file. This will increase CI times for linting in several of our packages. See: Very slow with typescript-eslint parser and project vuejs/vue-eslint-parser#65

Todo:

• Ensure autofix did not break any builds. There were changes to tsconfigs, which may impact this:
  • typescript-eslint parses .js files too, so that enabling recommended typings goes smoother - ts files that import js files can get some modicum of checking.
  • Several packages have new tsconfig.json files in their cypress/ and/or test/ directories. This is to help typescript-eslint's projectServer functionality determine which files should be included or excluded from the project (and thus linting)
• Several packages' eslint.config.ts files may have redundancies with the baseConfig in the root eslint.config.ts file. These are from partial application of DRY's "rule of three," and can probably be removed.
• Turn "gold standard" rules to "warn" - they were turned off to more easily resolve errors. Those that can be --fixed will likely result in very large diffs, so switching them on may warrant additional PRs.

Steps to test

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation?
• Have API changes been updated in the type definitions?

[cacieprins]

These should be ordered by:

1. originating ruleset (cypress/ before react/, etc)
2. impact of not fixing the rule.: rules that help prevent runtime errors or bugs should be prioritized over more superficial rules.

[MikeMcC399]

@cacieprins

• You can write "closes Remove dependency on ESLint v8 (EOL) #30386" in your PR

[cacieprins]

these options are no longer valid in vscode

[cacieprins]

This file was re-sorted by prettier-package-json https://www.npmjs.com/package/prettier-package-json

[cypress]

cypress    Run #59942

Run Properties:   Failed #59942  •  3a27427564: ignore .d.ts files in system-tests

Project	cypress
Branch Review	eslint-stylistic
Run status	Failed #59942
Run duration	12m 26s
Commit	3a27427564: ignore .d.ts files in system-tests
Committer	Cacie Prins
View all properties for this run ↗︎

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Test results
Failures	134
Flaky	0
Pending	99
Skipped	54
Passing	3454
View all changes introduced in this branch ↗︎

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Warning

Partial Report: The results for the Application Quality reports may be incomplete.

UI Coverage  41.86%
Untested elements	72
Tested elements	54

Accessibility  95.19%
Failed rules	0 critical   4 serious   0 moderate   0 minor
Failed elements	165

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Tests for review

  commands/traversals.cy.js • 0 failed tests • 5x-driver-firefox

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  commands/net_stubbing.cy.ts • 0 failed tests • 5x-driver-firefox

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  commands/actions/type_special_chars.cy.js • 0 failed tests • 5x-driver-firefox

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  commands/cookies.cy.js • 0 failed tests • 5x-driver-firefox

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Test		Artifacts

  e2e/origin/cookie_behavior.cy.ts • 0 failed tests • 5x-driver-firefox

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Test		Artifacts

The first 5 failed specs are shown, see all 1184 specs in Cypress Cloud.